Select arcade mode and play as a Federation pilot. Choose the first stage and wait until you get to a desert mission you should be fighting one Zaku2, one Gouf and an ADZAM mobile armor. Target the ADZAM and destroy it to unlock it in versus mode.

Play as Big-Zam

Select arcade mode and play as a Federation pilot. The easiest way to encounter it is to choose the fourth stage. Kill it to unlock it in versus mode. The only way to kill it with most Mobile Suits (or Gundams) is to jump up and hit its main body with your Beam Sword.

Play as Braw-Bro

Select arcade mode and play as a Federation pilot. Choose either the third or fourth stage, and at the second to last mission you will fight a mobile armor called BRAW-BRO. Kill it yourself to unlock it in versus mode. Note: This will not work if an ally makes the kill.

Play as G-Bull

Select arcade mode and play as a Zeon pilot. Choose the second or third stage. Play until you reaching a space battle where you will fight the G-BULL and one other Mobile Suit. Target and destroy the G-BULL to unlock it in versus mode.

Play as G-Fighter

Select arcade mode and play as a Zeon pilot. Choose the fourth stage and play until reaching the second to last mission. You will fight a Guntank and the G-FIGHTER. Target and destroy the G-FIGHTER to unlock it in versus mode.

Play as GRABRO

Select arcade mode and play as a Federation pilot. Choose one of the four stages and wait until you get to a mission where Zeon forces are attacking a base called Belfast. Target the GRABRO and just keep shooting it until it explodes to unlock it in versus mode. Note: This will not work if an ally makes the kill.

Play as G-Sky

Select arcade mode and play as a Zeon pilot. Choose the fourth stage and play until reaching a battle in space where you fight a Gelgoog and the G-SKY. Target and kill the G-SKY to unlock it in versus mode.

Extra mode

Successfully complete and save the game in campaign mode with both the Federation and Zeon. Select campaign mode again, and an "Extra" option will appear. In this mode, all Mobile Suits from both sides will be available in more difficult missions.

Alternate Mobile Suite color

Select versus mode and select "Choose A Mobile Suit" Find a mobile suit on the Zeon side, but have the team you want to be on the Federation side. When the level starts, the Zeon mobile suit you had chose will be a different color. Note: This only works on Mobile Suits and not Mobile Armors.

Hijack Mobile Suits

To hijack or steal a Mobile Suit in the story mode, you must end a mission with an enemy Mobile Suit still alive but with some damage. Chances are that if it is the only Suit besides you and your ally, you will see a message similar to "You have received a stolen GM". You can use it for ground combat." To get the hijacked Suits for arcade and the versus mode, kill one in arcade mode and survive the battle in which you killed it. When you open the versus mode or arcade mode, it will be there, ready for duty.

The Titans and the air and spacecraft

To unlock jets, submarines, spacecraft , and Titan class mobile armors, locate one in versus mode, weaken it, and deliver the final blow yourself. If an ally does the final shot, you will not unlock it. Once you kill it and save, it will be available for use in versus mode. An example is the G Fighter. Mobile Suits can jump on and ride it while the other player steers. Press R2 to cut thrusters and sit there. Another example is the Byg Zam. It is a two legged ball with a lot of particle cannons and a shield that makes it invincible to beam weapons.

Good fighting Suits

Some of the best Suits for arcade and versus mode are the Zaku II and the two GMs. All three of these suits have about 400 armor health points, very good weapons at their disposal, and are quite fast and good all around. Most people dismiss them as simple walking targets but they can pack a punch with some practice.

Defeating Big Zam

Take out the Rick Doms by using Gundam with your Beam Saber, then get behind the Big Zam and fire your Bazooka. Beam Rifles have no effect. When you run out of ammunition, switch to Beam Saber, jump, and slash.